The objective of this research is to evaluate a computer-assisted, continuous method for measuring breathlessness during exercise. The method represents a new approach to obtain subjective ratings from patients exercising on a cycle ergometer or treadmill. Whereas the "gold standard" Borg scale for measuring breathlessness is employed in over one million patients per year, it is limited by the fact that each estimate occurs at a discrete point in time cued or signaled by the health professional, rather than when the patient senses a change in symptom intensity. Moreover, if the patient cannot verbalize a response (e.g., while breathing through a mouthpiece), the rating must be indicated on the scale by finger pointing. During exercise this can lead to uncertainty on the part of the clinician as to exactly where the patient is pointing. The continuous method for obtaining patient-initiated ratings is unencumbered by these limitations, while also providing a direct measure of the absolute threshold and peak of breathlessness. The software to obtain such ratings has been shown to be reliable, valid, and easy to use. Thus far, the method has been successfully applied in patients with chronic obstructive pulmonary disease. The goal of Phase II is to evaluate the new methodology with a wider sample of adult patients afflicted with asthma, interstitial lung disease, respiratory muscle weakness, and pulmonary vascular disease, as well as with a group of children with asthma. Tests will also be conducted to investigate the responsiveness of the continuous method to track the effects of bronchodilator therapy and respiratory load. PROPOSED COMMERCIAL APPLICATION. The commercial goal is to replace the discrete scale with a computer-administered continuous method for measuring breathlessness during exercise. The product marketed in Phase III will be a computer software package that will be purchased by physicians, clinics and hospitals throughout the world. [unreadable] [unreadable]